will rear end out of 1994 ram with 354 gear bolt in my 69 dart

 

There's a guy on YouTube that did that swap, I'm not sure what he did for axles as the ram has 5 on 5 1/2 bolt pattern.

 

Does anyone know if a 71 Barracuda 8 1/4 rear end fit a 74 Duster?

 

You need a Bbody axle assembly the Cuda/Challenger axle assembly is wider by 3 inchs or so. The Bbody is wider than the Abody by 2.5 inchs but it works for an Abody. You will need to pay attention to your wheels back spacing though...